1. Field of the Invention
The present invention relates to a record/playback apparatus for recording and reproducing digitized and data compressed video signals having different in frequency bandwidths including a standard 4:3 aspect ratio TV signal, a 16:9 wide-screen TV signal, and a high-definition TV signal.
2. Description of the Prior Art
For improvement of recording and transmitting efficiency of a video signal which carries a large amount of data, high-efficiency encoding techniques are used to decimate the data amount without sacrificing image quality in reproduction. One such technique is orthogonal transform encoding in which a video signal is divided into blocks and the data of each block is encoded by frequency division. In particular, the data decimation is executed by reducing data at a high frequency range which carries image data less noticeable with the visual perceptivity of human eyes. The orthogonal transformation is commonly conducted by discrete cosine transforming non-interlaced data of each frame of the video signal.
As is understood, the input video signal to be processed is not one specific signal but a variety of different bandwidth signals including a standard TV signal for the 4:3 aspect ratio, a 16:9 wide-screen TV signal, and a high-definition TV signal having a wider bandwidth. For reproduction of such a discrete bandwidth width accuracy, each TV signal has to be sampled at a particular frequency for digitization. For digitizing the wider bandwidth of a TV signal, a high rate of the sampling frequency is needed and the amount of total data cannot be small. If the different TV signals are high efficiency encoded at one compression rate, the encoded or recording data of a wider bandwidth signal will be increased proportionally. If the recording data of each TV signal is uniform, the wider bandwidth signal will be more decimated producing an image of less quality.
For overcoming the drawbacks in processing a wider bandwidth video signal, there is provided a method of compressing interframe difference data of the video signal for eliminating redundancy in the timebase direction in addition to an interframe compression coding in which the video signal is spatially compressed. However, the interframe compression coding requires an extra local decoder circuit in its encoding circuit which is thus increased in overall size.